Natures-Answers

Are you getting enough?
…water, I mean?

Water is arguably the most important substance (along with air) on the planet. The sea was the birthplace of life on Earth and all known life depends on it to a greater or lesser extent. For us humans (just in case you were wondering if a thousand monkeys had written this), water makes up a large proportion of our bodies’ make-up and after the air we breathe, is the substance most vital to our survival.

But it’s not just survival we’re talking about – it’s staying healthy. The water in your body is there for a reason (several reasons actually) and it’s important that we maintain the correct levels. So what exactly does water do for us? As it turns out, even more than the Romans!

Water helps eliminate waste, especially through urine and sweat, helps regulate the body’s temperature, it carries nutrients to cells, aids in the maintenance of tissue structure, provides lubrication and is a medium for many of the chemical processes which occur in your body, including digestion of food; to the extent that some survival experts recommend eating little or nothing when lack of water is the main threat. However, as we get 20% of our fluids from food, you have to take the type of food into account. Most vegetables, for example, have a relatively high water content.

Hence, the first of many contradictions among people who profess to be experts. What follows is my attempt at answering the most common questions.

Contradictions about water for health

Unfortunately, as with most things, even the opinion of experts is far from unanimous and, for every person who claims evidence on one side, someone else will point to other research that contradicts it. Most sources will say you should drink 8 (x 8oz) glasses of water a day, while some experts have called that a myth. Opinions on whether tea, coffee, beer and other drinks count are split down the middle.

The best we can do is to gather the most commonly held beliefs of current scientific thinking and point out the range of difference where evidence is lacking.

De-hydration – Problems of too little water

Personally, I’m fortunate to have been mostly very healthy so far (touch wood) but I am prone to get headaches now and then and, after trying to identify the cause from the ‘usual suspects’, I have found that, in fact, the main culprit for me seems to be dehydration. And I don’t just mean from hangovers! The latter, though, are caused by a shortage of water in the body, which tries to take it from the brain, leading to a severe headache.

I suspect that many other people suffer similar problems to me and don’t even realise it. Other symptoms include a dry mouth, tiredness, lack of concentration, confusion and irritability. Excessive exposure to heat , especially in humid conditions, can lead to heat stroke because increased humidity prevents sweat evaporating from the skin to cool the body. More serious problems of severe dehydration include constipation and long term it can lead to kidney stones, blood clots, heart attack or stroke, as it can increase the viscosity of blood.

How much water should we drink?

The only correct answer is “enough, but not too much”!
What this translates to obviously depends on a number of factors, including where you live, body mass and age but varies between 1.5 and 3 litres per day in a temperate climate. The oft-quoted amount is 64oz – or 8 glasses per day.

However, nobody seems to know where this figure emanated from or whether it includes the 20% of fluid we get from food. Some experts think this is an exaggeration and that six glasses would be sufficient under normal circumstances. However it depends so much on other factors that it seems to me a moot point.

Children, depending on age, should drink about less than adults but slightly more in relation to their body weight.

If you’re doing heavy exercise, especially in hot weather, or if you have a dehydrating illness such as diarrhoea or vomiting, then you should drink more. Athletes under such circumstances can lose 10 litres a day.

Oh, and if you’re crossing the sahara desert, take a LOT more. Some medicines, such as diuretics and others can also increase dehydration.

There is some evidence that elderly people might drink – and need – less than younger people, but whether that is down to less activity is unclear.

How can I tell if I’m getting the right amount of fluid?

It’s easy to think that the answer is simple – when you get thirsty, have a drink. And that is exactly what some people say we should do. Certainly, if you are thirsty, you should drink, but some people only notice thirst when they’re already slightly dehydrated. This can be due to lack of sensitivity to their body’s requests or just due to concentration on other things, at work, for example.

So as a way of maintaining a good water balance, rather than topping it up afterwards, it can be a bit late.

Adding to the argument for drinking water regularly rather than relying on thirst is the fact that there may be a slightly higher risk of dehydration in elderly people due to a reduced thirst response and, perhaps, a reluctance to drink in the evening in case it means a visit to the bathroom in the night.

Another way of monitoring your hydration level is by the  frequency or toilet visits and colour of your urine.

Pale straw colour = good;
Darker yellow probably indicates that you should drink more.

Mild dehydration should be remedied fairly quickly by drinking water, but anyone suffering from the the more severe symptoms should consult their doctor.

Alternatives to Water

“But water’s a bit tasteless. Does anything else count?”
The good news is – yes, up to a point.

There will always be purists who believe that such drinks as tea and coffee should be avoided, or limited at least, and not included in your water intake amount, but although tea and coffee contain caffeine, which has diuretic properties, the amounts are low enough to be relatively insignificant and most authorities seem to believe that tea, coffee, milk or fruit juice do count as part of your water intake and some drinks may also include other useful nutrients.

Being English, I know a number of people whose fluid intake would be practically zero if you didn’t include tea! Many people claim that simply adding flavouring, such as lemon, to water can help, and studies have shown that people do indeed consume more fluid if the drink is flavoured in some way. Although claims are made for the presence of, say, lemon in its own right, it seems likely that the increased tendency to drink, regardless of the nature of the flavouring, is the most important factor. However, some commercial flavoured water also contains sugar and should be avoided.

Also be aware that these options are not necessarily direct equivalents in terms of quantitity; a cup of coffee is not the same as the equal volume of water and should only provide part of the overall intake, not replacing water completely.

Isotonic sports drinks can be useful before and after exercise as these drinks are  designed, supposedly, to enter and re-hydrate the system more quickly than plain water, a fact which sports scientists claim is little understood outside of the sports science world. However, you may only get any such benefit from heavy workouts of more than about 45 minutes; otherwise, you may be better off sticking to water. A healthy alternative to commercial sports drinks is coconut water, which also contains electrolytes.

Other soft drinks also count technically in terms of water content, but may be unhealthy in other ways – sugar content in fizzy drinks, for example.

Does beer count as water intake?

“Older civilizations drank beer or wine didn’t they? So what about alcohol?”

For much of European history, beer was drunk, even by children, because it was safer than drinking water which was often unclean and could lead to illness. Depending on where you read it, there are two reasons given for beer being safer:

• the alcohol and acids & tannins killed bacteria and other nasties; or
• the water to make the beer was boiled.

Take your pick. Like Greek wine, the beer was very weak by today’s standards so that the level of water content was far greater than any diuretic effect of the alcohol content.

Nevertheless, you’ll be glad to hear that even modern, moderate strength, beers can help to hydrate you as level of water content is still a little greater than the diuretic effect of the alcohol but it’s not a direct replacement for water as it does make you visit the toilet more often.

So, in the theoretical Sahara-crossing trip to which I referred earlier, if you ran out of water and, dreaming of a cold beer (like John Mills in ‘Ice cold in Alex’) came across a man on a camel who offered exactly that but couldn’t give you water (an unlikely scenario, I grant you) I’d take the beer. But that’s not quite the same as a long-term policy of daily fluid intake.

If you know your Homer (the Ancient Greek epic poet, that is, not the Simpson) you’ll have noticed that there are lot of references to drinking wine, but they diluted their wine with water so, again, it was a lot weaker than your average bottle of pinot noir.

Today, wines and spirits are not a substitute for water because the alcohol content makes them a more severe diuretic than tea or coffee or beer. It dehydrates by inhibiting production of vasopressin or ADH (anti-diuretic hormone). Vasopressin helps the body absorb and distribute water and controls the kidneys’ release of water in urine. When dehydrated, the kidneys reduce the level of water in urine (making it darker).

The lack of vasopressin due to alcohol means that water is sent from the kidneys directly to the bladder so more water is released and you go to the toilet more often and hence become dehydrated.

When you do drink alcohol, you can reduce its effects – and the possibility of a hangover – by drinking water beforehand and at the same time. (Well alongside, not from two glasses simultaneously, you understand – unless you want to make a fool of yourself. Mind you, drink too much alcohol and you may risk doing that anyway!)

Does it matter which type of water I drink?

There are different answers to this. From a hydration point of view, tap water is fine, as long as it’s known to be clean. In some countries, it isn’t and bottled water is a safer bet.

As to mineral water vs. bottled water vs. tap water, the jury is still out – and such is the strength of feeling about it, it may never come in! Part of the problem lies in inconsistency in what the alternatives mean.

Much bottled water is little or no more than tap water, and may contain more harmful pollutants which are bad for you, than water from your own tap.

Furthermore, the use (and especially, re-use) of some plastic bottles has been linked to a number of health problems, including cancer.

The minerals in mineral water can be obtained from other food sources and clean tap water is generally (though not necessarily well-) regulated.

For some of the arguments, see
http://www.helium.com/debates/102343-does-drinking-mineral-water-have-health-benefits/side_by_side.

On the other hand, some medical authorities are critical of the level of certain impurities in tap water in the USA, including the presence of Arsenic, Aluminium and Fluoride.

If you’re concerned, the best bet, short of drinking mountain spring water you collect yourself, which may be a little impractical if you live in London, is probably to drink either a particular brand of mineral water which you know to be reliably sourced (and don;t re-use the bottle), or to drink filtered tap water.

Water, water everywhere, nor any drop to drink
(Samuel Taylor Coleridge, The Rime of the Ancient Mariner)

Ok, so you’ve survived running out of water in the sahara and, on your next adventure, you’re shipwrecked… (Not having much luck are you?)

Swim in it, fish in it, but don't drink it!

The sun is shining, you’re thirsty and surrounded by water. What’s the problem?

The problem is twofold. Cells in the body are hydrated by osmosis in which the salinated water, both inside and outside the cell wall, is maintained at an equal (isotonic) concentration. As the cell uses up water, the concentration of salt increases, so the lighter fluid (lighter in salt concentration that is – not the stuff you put in your Zippo) from outside is drawn in through the cell membrane to equalise the balance.

When sea-water is consumed, the level of salt is far higher than that inside the cell so, no matter how dehydrated you are, water rushes out of the cell to maintain that balance. The cells don’t ‘know’ that you’re dehydrated, it is just a physical process, so just when your cells need more water they’re losing more.

Furthermore, the kidneys can only make urine that is less salty than sea-water. To rid the body of the salt taken in by drinking sea-water, you would have to urinate more water than you drank. So you become more dehydrated, not less. The kidneys cannot cope with the increasing salt level and eventually shut down, ultimately causing death.

Now you might be thinking: “If I had some fresh water and mixed it with a little sea water to lower the salinity to a level the cells and the kidneys could cope with, would that extend the period I would have fresh water?”

There is an argument which promotes that idea, but even if it worked, the amount of fresh water you would need as a ratio would probably make it not worth the risk, and most survival manuals – consistently consider any intake of sea-water an absolute no-no.

Is there a best time to drink water?

It is generally thought that drinking frequently throughout the day is better than trying to stock up like a car’s fuel tank, or, worse still, make up for a deficiency later on. Drinking in the morning on waking can be a good idea as you may not have drunk anything for eight hours. Likewise, drinking a little before bedtime can keep you going throughout the night, (On the other hand, if you drink too much, it could keep you going throughout the night!)

Advice on drinking water before and after meals varies greatly:

• between 30 mins and 90 mins before meals,
• at least one source says ‘2 glasses around main meal’,
• others say between 30 and 150 mins after meals,
• some reckon that drinking during meals or within 30 minutes ‘interferes’ with digestion.

Some claim specific reasons for particular times e.g.

• 30 minutes before meal: help digestion
• after waking up: helps activate internal organs
• before sleep: to avoid stroke or heart attack
• before taking a bath: helps lower blood pressure.

Exercise:
20 -30 mins before exercise, within 20 -30 mins after exercise.

Can you drink too much water?

Excessive consumption of anything can be poisonous so it is possible, although unlikely for most people under normal circumstances.

Water intoxication can mean the kidneys are unable to cope, which can lead to swelling of the brain. Symptoms, ironically, are not unlike those for dehydration – including headaches, confusion and nausea. In extreme cases, it can lead to coma and, in rare cases, ultimately prove fatal.

Drinking excessive amounts of water can be the caused by illnesses which affect the body’s water balance, such as kidney failure or cirrhosis of the liver, and by some drugs, including illegal ones such as ecstasy.  The biggest risks, though, are probably from water drinking contests, or from athletes who drink large amounts to rehydrate but do not sufficiently replenish electrolytes (minerals such as sodium, potassium, calcium etc.)

Over-hydration can lead to Hyponatremia, a dangerously low level of Sodium, which helps amongst other things to help transport water around the body.

Aa well as older people possibly having an increased risk of dehydration (see above), it is also possible that the risk of over-hydration is greater in some elderly people due to a lessened movement of water through the system.

I can still hear some sceptical Monty Python fans saying:
“Yes, but apart from keeping us alive, allowing chemical processes, aiding digestion, lubrication and cell growth, preventing kidney failure, headaches and hangovers, eliminating waste and preventing us from frying, just what does water do for us?”